2k2 Neon Won't Pass Emissions Test

[Mr_V]

I have a 2002 Neon, and a few weeks ago the check engine light came on. The car was due for an inspection so I went ahead and did the basic maintenance such as changing the oil, spark plugs, spark plug wires, etc. The car itself runs just fine without any real problems.

I took it to a shop to have the inspections done, and the car failed the emissions test. I was given a print out saying that there was a small emissions leak somewhere on the car, but they couldn't tell me where.

I then took the car to a local Advance Auto store to have them run a test on the computer and the result was a bit different. Their computer said that there is a small emis leak, and a large emis leak. They recommended putting on a new gas cap as that can sometimes cause the issue. I did so, and the light stayed on.

I ended up taking it to another shop as they said they could clear the codes and inspect the car before the system trips again. Well, the car has been at their shop for days now. They claim that they have to clear the computer, then drive the car to have it trip over and over, and that the car keeps giving different codes each time. I told them to just fix whatever the problem is, and not worry about trying to bypass it in order to pass inspection.

I was told that there was nothing wrong with the car and that the computer is just spitting out codes for no reason. I actually picked the car up today because they cannot get the check engine light to come back on, but the car still won't pass inspection with the light off. When it comes to cars, I can do the basics as I mentioned earlier in the post. When it comes to the computer and codes and such, I have no idea whats going on.

Is it necessary to keep reseting the computer and all that, as the shop is saying? North Carolina law says that if you spend over $200 on finding the emissions problem, and it is not found, then you can get a year long waiver on the inspection. I'm wondering if the shop is just jerking me around, and will charge me 200 for nothing and hand me a waiver.

I have to take the car back Monday as they hope the check engine light will be back on by that point. Any ideas why the car won't pass when the check engine light is off, and when the car is not giving any error codes? Also, do you guys have any ideas as to anything else I can try? I'm starting to get quite frustrated with the situation as I haven't had my car in about 5 days because of the inspection.

Any help you guys can provide will be MUCH appreciated.

[das2123]

Originally Posted by Mr_V

Any ideas why the car won't pass when the check engine light is off, and when the car is not giving any error codes?

If you just reset the PCM and try to test it will fail because some if not all the sensors aren't ready to be tested, like the O2 sensors. Those are needed for the emissions test. After restetting the PCM you have to drive the car at least 50 miles for the sensors to be ready. The only place that I can think of right now that could leak emissions would be the cat converter or exhaust.

[riverat440]

Actually the car won't pass emissions after the pcm is cleared because there are readiness monitors which haven't been set yet. When the pcm is cleared it has to go through a series of testing each emission system for example the EGR,oxygen heater, evaporative and so on. The 50 mile thing is an average for most. The truth is there is a specific driving cycle for each system which must be met. For example the catalyst(O2) on most says it must be driven for 5 minutes at a steady speed above 50 mph and then idled for 2 minutes in drive (for an automatic). I have seen people put 200 miles or more on some Neons trying to get them to pass. With PA emissions you can have all but 2 readiness monitors set to pass on 96-01 models and all but 1 on 01 up models. On the other hand if conditions are right I've seen a Saturn clear the monitors in 20 miles. When you try to explain some of this to a customer they sometimes act as if you are talking a different language. The best advice so far that I have seen is if your light is on get it in early so you will have enough time to get it to pass.

[das2123]

50 miles worked for me just fine!